The present disclosure relates to an articulated scissor duct, and more particularly to a damped scissors duct.
In some launch vehicles, in flight trajectory control is provided through steerable rocket engines. Such steerability may be achieved by interconnecting actuators to a gimbaled rocket engine. To accommodate such steerability, propellant lines may utilize flexible interconnects often known as flex joints. Such flex joints may include multiple bellows fabricated from stainless steel which can be stretched, compressed or angulated to provide the steerability required
Flex joints may be subject to unstable flow regimes in which fluids that flow along internal convolutions of the flex joint bellows may produce flow disturbances. One type of flow disturbance is flow induced vortex shedding. Flow induced vortex shedding is an unsteady flow that may occur at certain fluid flow velocities. The flow disturbances and structural response may result in feedback which may cause large displacements of the bellows convolutions and high cycle fatigue.
Usually, attempts are made to confine the flow velocity to regimes that do not have the potential to excite the bellow convolutions, but this may be difficult in systems with a highly throttleable flow.